EP1388238B1 - System and method for the parallel transmission of real-time critical and non real-time critical data via switched data networks, especially ethernet - Google Patents

Abstract

A system and a method provide a real-time-critical communication and a non-real-time-critical communication in a switched data network consisting of users and switching units, for example a distributed automation system, by a cyclic operation. In a transmission cycle, there exists for all users and switching units of the switched data network in each case at least one section for transmitting real-time-critical data and at least one section for transmitting non-real-time-critical data, as a result of which the real-time-critical communication is separated from the non-real-time-critical communication. Since all users and switching units are always synchronized to a common time base, the respective sections for transmitting data in each case take place at the same time for all users and switching units, i.e. the real-time-critical communication takes place independently in time from the non-real-time-critical communication.

Description

The invention relates to a system and method for the parallel transmission of real-time critical and non real-time critical data via switchable data networks, in particular Ethernet.

Data networks allow communication between several participants through networking, ie connection of the individual participants with each other. Communication means the transmission of data between the participants. The data to be transmitted are sent as data telegrams, ie, the data is packed into several packets and sent in this form over the data network to the appropriate recipient. This is why we also speak of data packets. The term transmission of data is used in this document completely synonymous with the above-mentioned transmission of data telegrams or data packets. The networking itself is achieved, for example, in switchable high-performance data networks, in particular Ethernet, in that at least one coupling unit is connected between two subscribers, which is connected to both subscribers. Each coupling unit can be connected to more than two participants. If the subscriber is integrated with a coupling unit, the coupling unit can also be connected only to another coupling unit or to another subscriber, ie to represent a terminal. Each participant is connected to at least one coupling unit but not directly to another participant. Participants are, for example, computers, programmable logic controllers (PLCs) or other machines that exchange electronic data with other machines, in particular process. Unlike bus systems, where each participant is every other participant of the data network can reach directly over the data bus, it is the switchable data networks exclusively to point-to-point connections, ie a subscriber can only indirectly all other participants of the switchable data network, by corresponding forwarding of the data to be transmitted by means of one or more Reaching coupling units.

In distributed automation systems, for example in the field of drive technology, certain data must arrive at specific times at specific times and be processed by the receivers. This is referred to as real-time critical data or data traffic, since an inaccurate arrival of the data at the destination leads to undesired results for the subscriber. According to IEC 61491, EN61491 SERCOS interface - Technical Description (http://www.sercos.de/english/index_english.htm), successful real-time critical data traffic of the type mentioned can be ensured in distributed automation systems.

From the US 5,654,969 An arrangement in a digital communication network is known for transmitting synchronously transferable first information, such as voice or video, and asynchronously transferable second information, such as data.

From the essay " Fixed and Movable Boundary Channel Access Schemes for Integrated Voice / Data Wireless Networks "by Jeffrey E. Wieselthier, IEEE Transactions on Communications, Volume 43, No. 1, January 1995, page 64-74 , a channel access method for radio networks is known, which allow a quasi simultaneous voice and data transmission. It takes into account the different requirements, which provide a voice and data transmission to transmission delay and error rate. Speech data is treated as real-time critical data and other data as non-real-time critical. The known radio data network is constructed between at least two subscribers, in particular a transmitter and a receiver, wherein the data is stored in at least a transmission cycle with adjustable time duration are transmitted. Each transmission cycle is subdivided into at least a first region for transmission of real-time critical data, namely the voice data, and at least a second region for transmission of non-real-time critical data. For non-real-time critical data, buffering is allowed, while for real-time critical data, it is not allowed because they need to be transmitted in near-real time in a continuous stream. If the channel capacity is busy, however, it may also happen that voice data, for example in the case of a new connection attempt, is blocked and thus lost.

The object of the invention is to provide a system and a method for the transmission of data via switchable data networks, in particular Ethernet, which allows a mixed operation of real-time critical and non real-time critical, in particular inter- or intranet-based data communication in the same data network.

This object is achieved by a method for transmitting data via switchable data networks, in particular Ethernet in the field of industrial installations, are transmitted in the real-time critical and non-real-time critical data, the switchable data network between at least two participants, in particular a transmitter and a receiver is constructed wherein the data is transmitted in at least one adjustable-length transmission cycle, each transmission cycle is transmitted in at least a first range for transmission of real-time critical data for real-time control and at least a second area is subdivided for transmission of non-real-time critical data.

This object is achieved by a system for transmitting data via switchable data networks, in particular Ethernet in the field of industrial facilities, with at least one data processing device which can be coupled to a data network, which transmits real-time-critical and non-real-time critical data, the switchable data network between at least two subscribers, in particular one Transmitter and a receiver, the system having means for transmitting data in at least one adjustable-length transmission cycle, each transmission cycle divided into at least a first real-time control real-time data transmission area and at least a second non-real-time data transmission area is.

The invention is based on the finding that an open Internet-based communication is spontaneous communication, ie that both the time of such communication and the amount of data that has to be transferred can not be determined beforehand. As a result, collisions on the transmission lines in bus systems or in the coupling units in switchable high-speed networks, in particular Fast Ethernet or Switched Ethernet, can not be ruled out. In order to be able to use the advantages of Internet communication technology also in real-time communication in switchable data networks in the field of automation technology, in particular drive technology, a mixed operation of real-time communication with other spontaneous, non-real-time critical communication, in particular Internet communication, is desirable. This is made possible by the fact that the real-time communication, which predominantly occurs cyclically in the application areas considered here and can thus be planned in advance, is not, in contrast, unforeseeable Real-time critical communication, especially open, Internet-based communication is strictly separated.

The communication between the subscribers takes place in transmission cycles, wherein each transmission cycle in at least a first range for transmitting real-time critical data for real-time control, such as the designated industrial facilities and at least a second area for transmitting non-real-time critical data, for example, the open, internet capable Communication is divided. A particularly advantageous embodiment of the invention is characterized in that each participant is assigned a coupling unit which is provided for transmitting and / or receiving and / or for forwarding the data to be transmitted.

An extremely advantageous embodiment of the invention is characterized in that all participants and switching units of the switchable data network by time synchronization with each other always have a common synchronous time base. This is a prerequisite for a separation of the plannable real-time communication from the unpredictable, non-real-time critical communication. The separation of the plannable real-time communication and the unpredictable, non-real-time critical communication is achieved by applying the time synchronization method according to the non-prepublished application DE 10004425.5 guaranteed. Through permanent use of this method even during operation of a distributed automation system all participants and switching units of the switchable data network are always synchronized to a common time base, which consequently means the same starting point and the same length of each transmission cycle for all participants and coupling units. Since all real-time critical data transmissions are known by the cyclic operation before the actual data transmission and therefore can be planned in advance, it is ensured that for all participants and coupling units the Real-time communication can be controlled so that no disturbances, such as collisions occur in the data transmission of the real-time critical data telegrams themselves and all planned critical data transfer times are met exactly.

A further particularly advantageous embodiment of the invention is characterized in that all non-real-time critical data which is to be transmitted during the intended range of real-time communication range of a transmission cycle, temporarily stored by the respective coupling unit and during the, not real-time critical communication provided this area or a subsequent transmission cycle, ie a non-scheduled Internet communication possibly occurring in the first area of a transmission cycle reserved for real-time communication is shifted to the second area of the transmission cycle reserved for spontaneous, non-real-time critical communication, thereby completely avoiding real-time communication disturbances. The corresponding data of the spontaneous, not real-time-critical communication are buffered by the respective coupling unit concerned and after the expiration of the real-time communication area only in the second area of the transmission cycle, which is reserved for the spontaneous, not real-time critical communication. This second area, i. the entire time period until the end of the transmission cycle is available to all subscribers for unpredictable, non-real-time critical communication, in particular internet communication, likewise without influencing the real-time communication since this is carried out separately in time.

Collisions with the real-time critical data telegrams in the coupling units can be avoided in that all non-real-time critical data provided during the, for the transmission of non-real-time critical data Range of a transmission cycle can not be transmitted, cached by the respective coupling unit and during the, intended for the transmission of the non-real-time critical data area of a subsequent transmission cycle.

A further advantageous embodiment of the invention is characterized in that the time duration of the area for the transmission of non-real-time critical data within a transmission cycle is automatically determined by the time duration of the area for the transmission of real-time critical data. The advantage of this arrangement is that in each case only the necessary transmission time is used for the real-time-critical data traffic and the remaining time is automatically available for non-real-time critical communication, for example for non-schedulable Internet communication or other non-real-time critical applications. It is particularly advantageous that the time duration of the range for transmitting real-time critical data within a transmission cycle is determined in each case by the connection-specific data to be transmitted, ie, the time duration of the two areas is determined for each individual data connection by the respectively required amount of data to be transmitted real-time critical data whereby the division of the two areas and thus the time available for non-real-time critical communication is optimized for each individual data connection between two coupling units for each transmission cycle.

A further advantageous embodiment of the invention is characterized in that the time duration of a transmission cycle is determined at least once prior to the respective execution of the data transmission. This has the advantage that at each start of a new, planned in advance data transmission, the duration of a transmission cycle to the respective requirements for real-time communication or open, Internet-enabled communication are tuned can. Of course, it is also possible that the duration of a transmission cycle and / or the duration of the range for transmitting real-time critical data of a transmission cycle can be changed as required, for example at previously scheduled, fixed times and / or after a planned number of transmission cycles, advantageously before the beginning of a transmission cycle by switching to other scheduled, real-time critical transmission cycles. Advantageously, the duration of a transmission cycle, depending on the application between one microsecond and ten seconds.

Another highly advantageous embodiment of the invention is characterized in that replanning of the real-time communication can be performed at any time during operation of an automation system, whereby a flexible adaptation of the real-time control is guaranteed at short term changing boundary conditions. As a result, a change in the duration of a transmission cycle is also possible.

A further advantageous embodiment of the invention is characterized in that a part of the intended for the transmission of real-time critical data range of the transmission cycle for the transmission of data to organize the data transmission is provided. It has proven to be of particular advantage in this case that the data telegrams for the organization of the data transmission are transmitted at the beginning of the area for the transmission of real-time-critical data of the transmission cycle. Data for the organization of the data transmission are, for example, data for the time synchronization of the subscribers and coupling units of the data network, data for the topology recognition of the network, etc.

A further advantageous embodiment of the invention is characterized in that for all to be transmitted, real-time critical data telegrams transmitting and receiving time all time points for the forwarding of the real-time critical data telegrams and the respective associated links via which the real-time critical data telegrams are forwarded before the start of the respective implementation of data transmission, ie it is in a coupling unit at stations and / or receivers and in each coupling units involved notes when and at which output port a real-time critical data telegram arriving at time X should be sent on.

Another highly advantageous embodiment of the invention is characterized in that the forwarding times are planned so that each real-time critical data telegram arrives at the latest forwarding time or earlier at the corresponding coupling unit, but it is forwarded in any case until the forwarding time. This eliminates the problem of time blurring, which is particularly noticeable in long transmission chains. As a result, the real-time-critical data telegrams can be transmitted or forwarded directly, without time interval, i. a worse use of bandwidth in real-time data packets is avoided. Of course, it is also possible if necessary to incorporate transmission pauses between the transmission of the individual data packets.

A further advantage of time-based forwarding is that the destination determination in the coupling unit is no longer address-based, because it is clear from the outset which port should be forwarded to. Thus, the optimal use of all existing links within the switchable data network is possible. Redundant links of the switchable data network, which should not be used for the address-based switching of non-real-time critical communication, because otherwise would be circularities of data packets, but can be considered in advance for the planning of the forwarding lines and thus used for real-time communication. This is the result Realization of redundant network topologies, eg rings for fault-tolerant real-time systems, possible. Data packets can be sent redundantly on disjoint paths, circularities of data packets do not occur. Another advantage of the forwarded forwarding is that the monitoring of each leg is thus possible without acknowledgment and a fault diagnosis is thus easy to carry out.

A further, extremely advantageous embodiment of the invention is characterized in that at least one arbitrary subscriber, in particular a subscriber with the ability to open, Internet-capable communication, with or without associated coupling unit, can be added to a switchable data network and it is ensured that critical Data transfers are performed successfully at the desired time, even if the arbitrary participant performs a non real-time critical communication, in particular Internet communication in parallel to a real-time critical communication.

A further, particularly advantageous embodiment of the invention is characterized in that a coupling unit is integrated into a subscriber. This results in an extraordinary cost advantage over the previously implemented as independent blocks coupling units, also called switches.

A further advantageous embodiment of the invention is characterized in that a coupling unit has two separate accesses to the respective subscriber, wherein an access for the exchange of real-time critical data and the other access for the exchange of non-real-time critical data is provided. This has the advantage that real-time critical and non-real-time critical data are processed separately. The access for the non-real-time critical data corresponds to the commercial interface of a regular Ethernet controller, whereby the previously existing software, In particular driver, without restriction is usable. The same applies to the hitherto existing software for a non-real-time capable data network.
In the following the invention with reference to the embodiments illustrated in the figures will be described and explained in more detail.

Show it:

FIG. 1

a schematic representation of an embodiment of a distributed automation system,

FIG. 2

the basic structure of a transmission cycle,

FIG. 3

the principle of operation in a switched network and

FIG. 4

a schematic representation of the interfaces between a local subscriber and a coupling unit.

FIG. 1 shows a schematic representation of an embodiment of a distributed automation system, wherein for reasons of clarity of presentation as part of the invention in each case the coupling unit is already integrated into the relevant participants. The prior art, in contrast, sees each of the coupling units integrated here already in the relevant local subscriber as their own device, which is in each case connected between two users. The integration of the respective coupling unit in a subscriber is cheaper and easier to maintain.

The automation system shown consists of several participants, which can be pronounced both as a sender and as a receiver at the same time, for example, from a control computer 1, several drives, where for reasons the clear representation of only the drive 2 is designated, and other computers 3, 4, 5, by means of connection cable, in particular Ethernet cable, where for reasons of clarity, only the connections 6a, 7a, 8a, 9a are designated, to a switchable data network , in particular Ethernet, are interconnected. The typical for the topology of an Ethernet coupling units in which, for reasons of clarity, only the coupling units 6, 7, 8, 9, 10 are designated, are already integrated into the respective participants in this presentation. The coupling units are used for transmitting and / or receiving and / or forwarding the data to be transmitted.

The control computer 1 is for example additionally connected to a company-internal communication network, for example intranet 11 and / or the worldwide communication network Internet 11. From the control computer 1 real-time critical data, for example, to control drive 2 via the connections 6a, 7a, 8a, 9a sent. This real-time critical data must be processed exactly at the time X of drive 2, otherwise unwanted effects, such as late startup of the drive 2, etc., occur, which disturb the functioning of the automation system. The respective forwarding of the real-time critical data is performed by the coupling units 6, 7, 8, 9 to the coupling unit 10, which transfers them to the receiver drive 2, from which the data are processed at the time X. In the prior art, a successful real-time critical data traffic of the type mentioned can be ensured, if in addition no other arbitrary communication, for example internet communication by computer 5, takes place at the same time. In this case, Internet communication at the same time by computer 5, computer 5 requests, for example, a website. These non-real-time critical data are forwarded via the connections 8a, 7a, 6a by means of the coupling units 9, 8 and 7 to the coupling unit 6, which the Data transfers to the computer 1, which finally sends the corresponding request to the Internet 11 and returns the answer via the same connections or coupling units in reverse order to computer 5. The answer uses the same way as the real-time critical communication. It can thus wait situation in the participating coupling units occur and the real-time critical data can no longer arrive on time at the drive 2. An error-free real-time operation can therefore no longer be guaranteed with the prior art. By contrast, the application of the disclosed invention makes it possible, in parallel to the real-time communication, to use any non-real-time-critical communication in the same data network without disturbing the real-time communication. This is indicated by the connection of the computers 3 and 4, in which no coupling unit is integrated and which are integrated by means of direct Ethernet connection in the illustrated automation system. The computers 3 and 4 do not participate in the real-time communication, but only in the spontaneous, Internet-capable, not real-time critical communication without disturbing the real-time communication.

The invention is based on the idea that real-time-critical and non-real-time-critical communication in switchable data networks is separated from one another such that the non-real-time critical communication does not have a disruptive effect on the real-time critical communication. Prerequisite for this separation is on the one hand, that all participants and switching units of the switchable data network by time synchronization with each other always have a common synchronous time base. This is done by permanent application of the time synchronization method according to the non-prepublished application DE 10004425.5 guaranteed during operation of a distributed automation system. The second prerequisite for the separation is the predictability of the real-time critical communication, which is given by the fact that the real-time communication in the application areas considered here in particular the drive technology cyclically occurs, ie a data transmission takes place in one or more transmission cycles.

In FIG. 2 is the expression of a basic structure of a transmission cycle which is divided into two areas, exemplified. A transmission cycle 12 is divided into a first area 13, which is provided for the transmission of real-time critical data, and a second area 14, which is provided for the transmission of non-real-time critical data. The length of the illustrated transmission cycle 12 symbolizes its duration 17, which is advantageously between one microsecond and ten seconds depending on the purpose. The time period 17 of a transmission cycle 12 is variable, but is determined at least once before the time of data transmission, for example by the control computer 1 and is the same length for all participants and switching units of the switchable data network. The time period 17 of a transmission cycle 12 and / or the time duration of the first area 13, which is provided for transmitting real-time critical data, may at any time, for example at previously scheduled, fixed times and / or after a planned number of transmission cycles, advantageously before the beginning of a transmission cycle 12 are changed by the control computer 1, for example, switches to other scheduled, real-time critical transmission cycles. In addition, the control computer 1 can at any time during operation of an automation system as required carry out new planning of the real-time communication, whereby also the time period 17 of a transmission cycle 12 can be changed. The absolute duration 17 of a transmission cycle 12 is a measure of the time proportion, or the bandwidth of the non-real-time critical communication during a transmission cycle 12, ie the time that is available for non-real-time critical communication. For example, non-real-time critical communication has a bandwidth of 30% for a period of time 17 of a transmission cycle 12 of 500us, a bandwidth of 97% for 10ms. In the first area 13, is provided for transmitting real-time critical data, a certain period of time for sending data telegrams for the organization of the data transmission 15 is reserved before sending the actual real-time critical data telegrams, of which for clarity, only the data message 16 is designated. The data telegrams for organizing the data transmission 15 include, for example, data for time synchronization of the participants and coupling units of the data network and / or data for topology detection of the network. After these data telegrams have been sent, the real-time critical data telegrams, or data telegram 16, are sent. Since the real-time communication through the cyclic operation can be planned in advance, the transmission times or the times for forwarding the real-time critical data telegrams before the start of data transmission are known for all, real-time critical data telegrams of a transmission cycle 12, respectively data telegram 16, ie the duration of the Area 14 for transmission of non-real-time critical data is automatically determined by the time duration of area 13 for transmission of real-time critical data. The advantage of this arrangement is that in each case only the necessary transmission time is used for the real-time critical data traffic and after its completion, the remaining time is automatically available for non-real-time critical communication, for example for non-schedulable Internet communication or other non-real-time critical applications. It is particularly advantageous that the time duration of the area 13 for the transmission of real-time critical data is determined in each case by the connection-specific data to be transmitted, ie, the time duration of the two areas is determined for each individual data connection by the respectively necessary amount of data to be transmitted real-time critical data, thereby the time division of area 13 and area 14 may be different for each individual data link for each transmission cycle 12. Only the necessary transmission time for the real-time-critical data traffic is used and the remaining time of a transmission cycle 12 is automatically available for the non-real-time critical communication, for example for the unpredictable Internet communication or other non-real-time critical applications for all participants of the switchable data network. Since the real-time communication is planned in advance in such a way that the arrival of the real-time critical data telegrams in the corresponding coupling units is planned such that the considered, real-time critical data telegrams, for example data telegram 16, arrive at the latest at the forwarding time or earlier at the corresponding coupling units, the real-time critical data telegrams can , respectively data telegram 16, are sent or forwarded without time interval, so that the available time period is used in the best possible way by the densely packed transmission or forwarding. Of course, it is also possible if necessary to incorporate transmission pauses between the transmission of the individual data telegrams.

FIG. 3 shows the principle of operation in a switched network. Shown are representative of a network, a participant 18, such as a drive, and a subscriber 19, for example, a control computer, each with integrated coupling units 20, 21 and another participant 36 without coupling unit, which are connected to each other by the data links 32, 33. In this case, the coupling unit 20 is connected via the external port 30, the data connection 32 and the external port 31 to the coupling unit 21. On the designation of the other illustrated external ports of the coupling units 20, 21 has been omitted for the sake of clarity. On the presentation of other participants with or without integrated coupling unit was also omitted for the sake of clarity. Data connections 34, 35 to other subscribers starting from the illustrated coupling units 20, 21 are only indicated. The coupling units 20, 21 each have local memory 24, 25, which via the internal interfaces 22, 23 are connected to the participants 18, 19. Via the interfaces 22, 23, the participants 18, 19 exchange data with the corresponding coupling units 20, 21. The local memories 24, 25 are connected within the coupling units 20, 21 via the data links 28, 29 to the control units 26, 27. The control units 26, 27 receive data or forward data via the internal data links 28, 29 from or to the local memories 24, 25 or via one or more of the external ports, for example port 30 or port 31. By applying the method of Time synchronization, the coupling units 20, 21 always have a common synchronous time base. If subscriber 21 has real-time-critical data, these are picked up at the time scheduled for the real-time critical communication via the interface 23, the local memory 25 and the connection 29 from the control unit 27 and from there via the provided external port, for example, port 31 to Coupling unit 20 sent. Sends subscriber 36 at the same time, so during real-time critical communication, not real-time critical data, for example, for an Internet query, via the data connection 33, they are received by the control unit 27 via the external port 37 and via the internal connection 29 to the local memory 25th forwarded and cached there. From there, they are only picked up again in the area for non-real-time critical communication and forwarded to the receiver, ie they are shifted to the second area of the transmission cycle, which is reserved for spontaneous, non-real-time critical communication, thereby excluding disturbances in real-time communication. In the event that not all cached, non-real-time critical data can be transmitted during the, intended for the transmission of non-real-time critical portion of a transmission cycle, they are cached in the local memory 25 of the coupling unit 21 until they during a, for the transmission the non-real-time critical data area of a later transmission cycle can be transmitted, whereby Disturbances of real-time communication are excluded in any case.
The real-time critical data telegrams, which arrive via data connection 32 via the external port 30 at the control unit 26 of the coupling unit 20, are forwarded directly via the corresponding external ports. This is possible because the real-time communication is planned in advance and therefore for all real-time critical data telegrams transmitting and receiving time, all participating coupling units and all times for forwarding and all receivers of the real-time critical data telegrams are known, ie it is for example at the control unit 26 of the coupling unit 20 notes that the incoming at the time X real-time critical data telegrams to be forwarded via the external port 38 to the next coupling unit. The planning in advance of the real-time communication also ensures that, for example, no data collisions occur on the data connection 34 starting from port 38. The same is of course true for all other data connections, or ports during real-time communication. The forwarding times of all real-time critical data packets from the coupling units involved in each case are also planned in advance and thus clearly defined. The arrival of the real-time critical data telegrams, for example, in the control unit 26 of the coupling unit 20 is therefore planned so that the considered, real-time critical data telegrams arrive at the latest forwarding time or earlier in the control unit 26 of the coupling unit 20. This eliminates the problem of time blurring, which is particularly noticeable in long transmission chains. Data intended, for example, for the subscriber 18 and buffered in the local memory 24 of the coupling unit 20 are fetched from it in due course, real-time critical data at the predetermined times and non-real-time critical data during the designated area.

As stated above, consequently, simultaneous operation of real-time-critical and non-real-time-critical communication in the same switchable data network and any connection of additional subscribers to the switchable data network is possible without disturbing the real-time communication itself.

FIG. 4 shows a schematic representation of the interfaces between a local subscriber and a coupling unit. The coupling unit 40 is integrated according to the disclosed invention in the subscriber 39, for example, a control computer 1 of an automation system. Participant 39 participates in both real-time critical and non-real-time critical communication, therefore real-time critical applications 48, for example for controlling drives of an automation system, and non-real-time critical applications 49, such as spontaneous internet communication or word processing software, are installed on the subscriber 39 , For reasons of clarity, only logical and no physical connections, in particular data connections are shown. The communication between subscriber 39 and integrated coupling unit 40 takes place via the local memory 41, in which the corresponding data, which are sent by subscriber 39 or intended for subscriber 39, are buffered. Both the subscriber 39 and the coupling unit 40 must be able to access the local memory 41; the physical location of the local memory 41, which in the exemplary embodiment shown is part of the coupling unit 40, for example, is not important here. In order to ensure the separation between real-time-critical and non-real-time communication and thus interference-free real-time communication, two separate accesses to the subscriber 39 are required, with one access for the exchange of real-time critical data and the other access for the exchange of non-real-time critical data. As a result, the physical communication takes place via two separate ones Logical interfaces 42 and 43, between the data network and the coupling unit 40, not shown for reasons of clarity, and the logically separate communication channels 46 and 47 between the memory 41, ie the coupling unit 40, and the subscriber 39th Die Schnittstelle 42 und die Kommunikationskanal 46 In this case, the communication channels for the real-time-critical, the interface 43 and the communication channel 47 characterize the communication channels for non-real-time critical communication. However, the two logically separated interfaces 42 and 43 and the communication channels 46 and 47 respectively shown are each physically the same communication channel used to communicate the respective data in both directions. In particular, the separate signaling which type of data is present and can be collected via the two logically separate communication channels 46 and 47, where via communication channel 46, the provision of real-time critical data for the real-time critical applications 48 and communication channel 47, the provision of non-real-time critical data for the non-real-time critical applications 49 is signaled. In this way, drivers 44 and the real-time-critical applications 48 can be processed with a higher priority than drivers 45 and the non-real-time critical applications 49. Thus real-time processing of the real-time-critical data can also be guaranteed in the subscriber 39. The separation of the real-time critical and the non real-time critical communication, which is necessary for ensuring the real-time communication, also has the advantage that existing non-real-time communication programs, especially existing drivers can be used without restriction, which on the one hand no expensive new developments are necessary and, on the other hand, the further evolution of non-real-time critical standard communication has no effect on real-time communication itself and therefore may be included without limitation in the disclosed invention.

In summary, the invention relates to a system and a method that enables both real-time critical and non-real-time critical communication in a switchable data network consisting of subscribers and switching units, for example, a distributed automation system by a cyclic operation. In a so-called transmission cycle (12), at least one area (13) for transmitting real-time critical and at least one area (14) for transmitting non-real time critical data exists for all users and switching units of the switchable data network, whereby the real-time critical is separated from the non-real-time critical communication. Since all subscribers and switching units are always synchronized to a common time base, the respective areas for transmitting data for all subscribers and switching units take place at the same time, i. Real-time critical communication takes place independently of time-critical communication and is therefore not influenced by it. Real-time critical communication is planned in advance. Feeding of the data telegrams at the originating transmitter and their forwarding by means of the participating coupling units is time-based. By buffering in the respective coupling units is achieved that occurring at any time, spontaneous, internet-capable, not real-time critical communication in the, provided for the non-real-time communication transmission range (14) of a transmission cycle (12) and also transmitted only there.

Claims (41)

1. Method for transmitting data via a data network, in which real-time-critical and non-real-time-critical data are transmitted, the data network being set up between at least two users, especially a transmitter and a receiver, the data being transmitted in at least one transmission cycle (12) with adjustable period (17), each transmission cycle (12) being subdivided into at least one first section (13) for the transmission of real-time-critical data and at least one second section (14) for the transmission of non-real-time-critical data, characterized in that the data network is a switched Ethernet data network in the field of industrial systems, in which each user is allocated a switching unit which is provided for transmitting and/or receiving and/or forwarding the data to be transmitted, that all switching units of the switched data network exhibit a common synchronous time base due to mutual timing synchronization, and that in all switching units involved in each case, all times for forwarding the real-time-critical data telegrams and the respective associated links via which the real-time-critical data telegrams are forwarded are noted before the beginning of the respective performance of the data transmission for all real-time-critical data telegrams to be transmitted for real-time control.
2. Method according to Claim 1, characterized in that all non-real-time-critical data which are intended to be transmitted during the section (13) of a transmission cycle (12) which is provided for the real-time-critical communication are temporarily stored by the respective switching unit and are transmitted during the section (14) of this or a subsequent transmission cycle which is intended for the non-real-time-critical communication.
3. Method according to Claim 1 or 2, characterized in that all non-real-time-critical data which cannot be transmitted during the section (14) of a transmission cycle (12) intended for the transmission of the non-real-time-critical data are temporarily stored by the respective switching unit and transmitted during the section (14) of a later transmission cycle which is intended for the transmission of the non-real-time-critical data.
4. Method according to one of the preceding claims, characterized in that the period of the section (14) for the transmission of non-real-time-critical data within a transmission cycle (12) is automatically established by the period of the section (13) for the transmission of real-time-critical data.
5. Method according to one of the preceding claims, characterized in that the period of the section (13) for the transmission of real-time-critical data within a transmission cycle (12) is in each case determined by the data to be transmitted in a connection-oriented manner.
6. Method according to one of the preceding claims, characterized in that the period (17) of a transmission cycle (12) is established at least once before the respective data transmission takes place.
7. Method according to one of the preceding claims, characterized in that the period (17) of a transmission cycle (12) and/or the period of the section (13) for the transmission of real-time-critical data of a transmission cycle (12) can be changed.
8. Method according to one of the preceding claims, characterized in that the period (17) of a transmission cycle (12) is between 1 microsecond and 10 seconds.
9. Method according to one of the preceding claims, characterized in that the real-time communication can be newly planned at any time during active operation of an automation system.
10. Method according to one of the preceding claims, characterized in that the period (17) of a transmission cycle (12) can be changed by newly planning the real-time communication.
11. Method according to one of the preceding claims, characterized in that a part of the section (13) of the transmission cycle (12) intended for the transmission of the real-time-critical data is intended for the transmission of data for the organization of the data transmission (15).
12. Method according to one of the preceding claims, characterized in that the data for the organization of the data transmission (15) are transmitted at the beginning of the section (13) for the transmission of real-time-critical data of the transmission cycle (12).
13. Method according to one of the preceding claims, characterized in that the data for the organization of the data transmission (15) contain data for the timing synchronization of the users and switching units of the data network and/or data for recognizing the topology of the network.
14. Method according to one of the preceding claims, characterized in that the transmitting and receiving time for all real-time-critical data telegrams to be transmitted are noted at the transmitter and/or receiver before the beginning of the respective performance of the data transmission.
15. Method according to one of the preceding claims, characterized in that each real-time-critical data telegram arrives at the corresponding switching unit at the latest at the forwarding time or earlier.
16. Method according to one of the preceding claims, characterized in that the real-time-critical data telegrams are transmitted or, respectively, forwarded immediately without time interval.
17. Method according to one of the preceding claims, characterized in that links of a switched data network which must not be used for the non-real-time-critical communication are used in the real-time-critical communication.
18. Method according to one of the preceding claims, characterized in that at least one user of a switched data network can perform a real-time-critical communication and/or a non-real-time-critical communication, especially an Internet communication, in parallel in the same switched data network, wherein the non-real-time-critical communication taking place does not influence the real-time-critical communication taking place in parallel.
19. Method according to one of the preceding claims, characterized in that at least one arbitrary user, especially a user having the capability for open Internet-capable communication, with or without associated switching unit, can be added to a switched data network.
20. System for transmitting data via a data network, comprising at least one data processing device which can be coupled to a switched data network and which transmits real-time-critical and non-real-time-critical data, the data network being set up between at least two users, especially a transmitter and a receiver, the system exhibiting at least one means for transmitting data in at least one transmission cycle (12) with adjustable period (17), each transmission cycle (12) being subdivided into at least one first section (13) for transmitting real-time-critical data and at least one second section (14) for transmitting non-real-time-critical data, characterized in that the data network is a switched Ethernet data network in the field of industrial systems, in which each user is allocated a switching unit which is provided for transmitting and/or receiving and/or forwarding the data to be transmitted, that the system exhibits at least one means which supplies all switching units of the switched data network with a common synchronous time base by means of mutual timing synchronization, and that the system exhibits at least one means which notes all times for the forwarding of the real-time-critical data telegrams and the respective associated links via which the real-time-critical data telegrams are forwarded for all real-time-critical data telegrams to be transmitted for real-time control in all switching units involved in each case, before the beginning of the respective performance of the data transmission.
21. System according to Claim 20, characterized in that the system exhibits at least one means which ensures that all non-real-time-critical data which are to be transmitted during the section (13) of a transmission cycle (12) intended for the real-time-critical communication are temporarily stored by the respective switching unit and are transmitted during the section (14), intended for the non-real-time-critical communication, of this or a subsequent transmission cycle.
22. System according to one of Claims 20 or 21, characterized in that the system exhibits at least one means which ensures that all non-real-time-critical data which cannot be transmitted during the section (14) of a transmission cycle (12) intended for the transmission of the non-real-time-critical data are temporarily stored by the respective switching unit and are transmitted during the section (14), intended for the transmission of the non-real-time-critical data, of a later transmission cycle.
23. System according to one of Claims 20 to 22, characterized in that the system exhibits at least one means which automatically establishes the period of the section (14) for the transmission of non-real-time-critical data within a transmission cycle (12) by means of the period of the section (13) for transmitting real-time-critical data.
24. System according to one of Claims 20 to 23, characterized in that the system exhibits at least one means which in each case determines the period of the section (13) for transmitting real-time-critical data within a transmission cycle (12) by means of the data to be transmitted in a connection-oriented manner.
25. System according to one of Claims 20 to 24, characterized in that the system exhibits at least one means which establishes the period (17) of a transmission cycle (12) at least once before the respective performance of the data transmission.
26. System according to one of Claims 20 to 25, characterized in that the system exhibits at least one means which changes the period (17) of a transmission cycle (12) and/or the period of the section (13) for the transmission of real-time-critical data of a transmission cycle (12).
27. System according to one of Claims 20 to 26, characterized in that the system exhibits at least one means which newly plans the real-time communication at any time during active operation of an automation system.
28. System according to one of Claims 20 to 27, characterized in that the system exhibits at least one means which changes the period (17) of a transmission cycle (12) by newly planning the real-time communication.
29. System according to one of Claims 20 to 28, characterized in that the system exhibits at least one means which provides a part of the section (13) of the transmission cycle (12) provided for the transmission of the real-time-critical data for the transmission of data for the organization of the data transmission (15).
30. System according to one of Claims 20 to 29, characterized in that the system exhibits at least one means which transmits the data for the organization of the data transmission (15) at the beginning of the section (13) for the transmission of the real-time-critical data of the transmission cycle (12).
31. System according to one of Claims 20 to 30, characterized in that the system exhibits at least one means which notes the transmitting and receiving time at the transmitter and/or receiver for all real-time-critical data telegrams to be transmitted before the beginning of the respective performance of the data transmission.
32. System according to one of Claims 20 to 31, characterized in that the system exhibits at least one means which ensures that each real-time-critical data telegram arrives at the corresponding switching unit at the latest at the forwarding time or earlier.
33. The system according to one of Claims 20 to 32, characterized in that the system exhibits at least one means which transmits or forwards the real-time-critical data telegrams immediately without time interval.
34. The system according to one of Claims 20 to 33, characterized in that the system exhibits at least one means which ensures that links of a switched data network which must not be used for the non-real-time-critical communication are used in the real-time-critical communication.
35. The system according to one of Claims 20 to 34, characterized in that a switching unit is integrated in a user.
36. The system according to one of Claims 20 to 35, characterized in that a switching unit has two separate accesses to the respective user, one access being intended for exchanging real-time-critical data and the other access being intended for exchanging non-real-time-critical data.
37. The system according to one of Claims 20 to 36, characterized in that the system exhibits at least one means which ensures that at least one user of a switched data network can perform a real-time-critical communication and/or a non-real-time-critical communication, especially an Internet communication, in parallel in the same switched data network, wherein the non-real-time-critical communication taking place does not influence the real-time-critical communication taking place in parallel.
38. The system according to one of Claims 20 to 37, characterized in that the system exhibits at least one means which ensures that at least one arbitrary user, especially a user with the capability for open Internet-capable communication, with or without associated switching unit, can be added to a switched data network.
39. User for a system according to one of Claims 20 to 38 and/or a user with means to carry out the method according to one of Claims 1 to 19.
40. User according to Claim 39, characterized in that the user is a user of an automation system.
41. User according to one of Claims 39 or 40, characterized in that the user exhibits at least one means for transmitting real-time-critical and non-real-time-critical data, the data being transmitted in at least one transmission cycle (12) with adjustable period (17), each transmission cycle (12) being subdivided into at least one first section (13) for transmitting real-time-critical data for real-time control and at least one second section (14) for transmitting non-real-time-critical data.

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